ICANN's Security and Stability Advisory Committee (SSAC) has issued a report "Overview and History of the IANA Functions". The report describes the activities included in the IANA Functions contract as well as the functions performed under the IETF MoU in order to establish a baseline of understanding for those interested in how the upper-most level of the Internet’s system of unique identifiers is managed. It focuses primarily on the IANA Functions contract, but is intended to describe all of the activities related to the IANA Functions as they are currently performed, including those that lie outside of the IANA Functions contract.

Report: https://www.icann.org/en/system/files/files/sac-067-en.pdf
Infographic: http://www.slideshare.net/icannpresentations/the-iana-functions
Twitter: #‎IANASteward‬